Heat exchanger



Se t. 25, 1962 J. R. MILLER HEAT EXCHANGER Filed May 3, 1960 m 0 Z w M l h. a n J a J 01 w w J 7; a, m; M 0 J7 m f W a 3 d 4 4 Z z V Y mm W a ,lNVE-N'TOR JOHN R- MILLER 777. 3 flu 14) ATTORNEY United States Patent Oiilice 3,055,641 Patented Sept. 25, 1962 3,055,641 HEAT EXCHANGER John R. Miller, West Hartford, Cohan, assignor to United Aircraft Corporation, East Hartford, Conn., a corporation of Delaware Filed May 3, 1960, Ser. No. 26,637 8 Claims. (Cl. 257-235) This invention relates to heat exchangers and has as one of its objects to provide an improved heat exchanger of the crossflow type.

Another object of this invention is to provide an improved heat exchanger of cylindrical configuration particularly adapted for use in axial-flow gas turbine engines in which the heat exchanger is concentric with and surrounds an axial shaft of the engine.

In such an installation it is proposed to discharge air from the engine compressor axially into one end of the cylindrical casing of the heat exchanger and to discharge the air axially at the other end of the casing into the engine turbine. Liquid metal, or some other suitable heattransfer fluid, is circulated through a heat source, which may be a nuclear reactor, and through banks of concentric semicircular tubes extending transverse to the axis of the casing between longitudinal headers within the casing.

A further object of this invention is generally to improve the construction and performance of heat exchangers.

These and other objects and advantages of the heat exchanger comprising this invention will be evident or will be pointed out in connection with the following detailed description of a preferred embodiment of the invention shown in the accompanying drawing. In this drawing:

FIG. 1 is a longitudinal radial section taken through the cylindrical heat exchanger of this invention;

FIG. 2 is a similar view on a smaller scale showing a diametrical section through the heat exchanger;

FIG. 3 is an end view taken on lines 3-3 of FIG. 2. with parts omitted to facilitate illustration;

FIG. 4 is an exploded sectional view through the innermost heat-transfer core; and

FIG. 5 is an end view on an enlarged scale of this innermost core, the view being taken on a section through the innermost headers between adjacent cores.

Referring to FIG. 2, the heat exchanger of this invention includes an outer cylindrical casing open at both ends through which one of the heat exchange fluids, here air, is axially directed. It will be noted that the casing is unobstructed in the vicinity of its longitudinal axis 12 so that an engine shaft may be extended axially through the casing. A radial inlet manifold 14 is provided at the upstream end of the heat exchanger and a diametrically opposite outlet manifold 16 is provided at the downstream end of the heat exchanger. Three longitudinal inlet headers 18, 20 and 22 are provided in fluid communication with the inlet manifold 14 and three longitudinal outlet headers 24, 26 and 28 are similarly connected to the outlet manifold 16.

Fluid flow between the inlet and outlet headers is accomplished through banks of semicircular tubes which connect the several headers. These are best shown in FIG. 3 where it will be seen that an outer bank 30 connects inlet header 18 with outlet header 28 on each side of these headers; an intermediate bank 32 connects inlet header 20 with outlet header 26 on each side of these headers; and an inner bank 34 connects inlet header 22 with outlet header 24 on each side of these headers. Herein, each bank consists of thirteen groups of three tubes each, the groups a, b, 0 through m, being arranged in spaced relation along the length of the headers, as is best shown in FIG. 1.

These groups of tubes are not disposed in radial planes, but rather lie in oblique planes as indicated in FIGS. 1 and 2. This arrangement provides an ofiset-flow pattern for the air flowing generally axially through the casing. The tubes of each bank have a conical ring 36 brazed to the three tubes on the upstream side thereof and a somewhat similar conical ring 38 brazed to the downstream side. These conical rings are of different diameters for the diiferent banks 30, 32, 34. Thus, banks 32 have smaller conical rings 40 and 42 and banks 34 have even smaller conical rings 44 and 46. These conical rings are preferably made in tWo semicircular pieces, as will be evident from FIG. 5, Where the upstream conical ring 44 is shown as comprised of two semicircular members 44a and 44b and ends of which are shaped to conform to and are Welded to the header members 22 and 24. Further, the upstream rings 36, 40 and 44 have their inner annular edges deflected upstream toward the oncoming air and these scoop-like edges 47 of the rings extend progressively farther into the air stream toward the downstream end of the heat exchanger. This is shown most clearly in FIG. 1. Additionally conical baflles 48 and 50 are provided in the annular spaces between adjacent banks of tubes which direct the air into the scoop-shaped edges of the rings, as indicated in FIG. 1. As a result, air which enters at the upstream end of casing 10 flows between each of the banks of tubes throughout the length of casing 10, as indicated by the arrows in FIG. 2.

The annular spaces between the longitudinally spaced groups of tubes a, b, 0, etc., are provided with semicircular corrugated sheets 52, one set of which is shown In the operation of th heat exchanger, air, which enters the upstream end of the heat exchanger over the entire circular area presented by the upstream end of casing 10, is deflected by the scooped edges of conical rings 36, 40 and 44 into the annular passages between adjacent groups of tubes (1, b, c, etc. The air is forced to travel in a radial direction by the corrugated sheets 52 which are secured to the adjacent conical rings in heat-conducting relationship. The heated air then is discharged axially at the downstream end of the casing.

The crossflow fluid, which may be liquid metal, for example, enters the inlet manifold 14 which supplies the three inlet headers 18, 20, 22. From these headers it flows through the semicircular banks of tubes to the three longitudinal outlet headers 24, 26 and 28 into the outlet.

and arrangement of the parts within the scope of the invention.

I claim:

1. In a heat exchanger, a cylindrical outer casing open at both ends through which a first fluid is directed from an inlet at one end to an outlet at the other end, said inlet and outlet extending over the entire cross-sectional area of said casing, a radial inlet manifold at the inlet of said casing which extends substantially to said casing,

axis, said inlet manifold being closed at its inner end and having a fiuid inlet at its outer end for a second fluid, a radial outlet manifold at the outlet end of said casing which extends from said casing substantially to said casing axis, said outlet manifold having its inner end closed and having a fluid outlet for said second fluid at its outer end, said inlet and outlet manifolds being diametrically opposite one another and at opposite ends of said casing, a plurality of axially extended header pipes connected with said inlet manifold at spaced points along its length, a plurality of axially extended header pipes connected with said outlet manifold at spaced points along its length, said header pipes extending the full length of said casing and being closed at their free ends, and banks of semicircular tubes connecting corresponding inlet and outlet header pipes along the length of said header pipes forming a cylindrical matrix which fills said outer casing, said banks of pipes lying in oblique planes and having their ends abutted to said header pipes, each bank of oblique pipes having a conical ring brazed to it on its upstream side and a conical ring brazed to it on its downstream side.

2. A heat exchanger as defined in claim 1 in which the upstream conical rings of the banks of tubes have their inner edges deflected upstream toward the oncoming first fluid.

3. A heat exchanger as defined in claim 2 in which conical baffles are provided in the annular spaces between the adjacent banks of concentric tubes which direct the first fluid into the scooped edges of the rings.

4. A heat exchanger as defined in claim 3 in which the inner scooped edge of each conical ring in a downstream direction is extended successively farther inward into the first fluid stream.

5. A heat exchanger as defined in claim 3 in which the inner scooped edge of each conical ring is extended in a downstream direction closer to the adjacent conical baflle.

6. A heat exchanger as defined in claim 3 in which the annular spaces between the banks of tubes are filled with semicircular corrugated sheets for directing the first fluid flow radially between the banks.

7. A heat exchanger as defined in claim 1 in which extended heat-transfer surfaces are provided in an inclined radial direction that is three-dimensional in an axial-radial sense so that the extended surface on the front side of one oblique bank of tubes can slide freely with respect to the extended surface on the back side of an adjacent obliqu bank of tubes as a result of differential thermal expansion or mechanical action.

8. In a heat exchanger, a cylindrical outer casing open at both ends through which a first fluid is axially directed, a plurality of inlet headers extending lengthwise of said casing, said inlet headers lying in a radial plane of said casing, a plurality of outlet headers extending lengthwise of said casing, said outlet headers lying in a radial plane of said casing diametrically opposite to the radial plane of said inlet headers, an inlet manifold supplying a second fluid to one end of said inlet headers, said inlet headers being closed at their opposite ends from said manifold, an outlet manifold collecting said second fluid from said outlet headers, said outlet headers being closed at their opposite ends from said outlet manifold, a plurality of banks of semicircular tubes connecting corresponding inlet and outlet headers along the length of the latter on both sides of said headers, each bank of tubes including a plurality of tubes arranged at an oblique angle to the header axis to which they are secured, a conical plate secured to the downstream side of each bank of tubes, a second conical plate secured to the upstream side of each bank of tubes, said upstream conical plates having their inner edges extended inwardly beyond said banks of tubes, each bank having its second conical plate extended inwardly slightly more than that connected to the next upstream bank, conical battles located in the annular spaces between certain of said headers extending downstream and outwardly, and two semicircular corrugated plates in the annular space between each downstream conical plate of each bank of tubes and the upstream conical plate of the next downstream bank of tubes.

References Cited in the file of this patent UNITED STATES PATENTS 632,506 Allington Sept. 5, 1899 2,160,898 Pefl June 6, 1939 2,606,006 Karlsson et al Aug. 5, 1952 2,739,795 Mueller Mar. :27, 1956 2,819,330 White Jan. 7, 1958 2,858,113 Miller Oct. 28, 1958 

